1. Technical Field
The present invention relates to a printing method.
2. Related Art
The market for a photocurable ink jet printer is expanding. When an ink jet printer ejects a water-based ink or an organic solvent-based ink, a media needs to absorb the solvent. However, the photocurable ink jet printer has an advantage that the media does not have to absorb the solvent. Therefore, the printer may be adapted to media formed of various materials.
A large-sized media such as a large-sized signboard, a banner, an indoor or outdoor display advertisement, a car sticker, a placard and an interior finishings is one of the applications of the photocurable ink jet printer. Therefore, a head needs to be enlarged to improve the printing speed. As one method to enlarge the head, there is a method in which a carriage is configured with a plurality of heads combined. However, if ends of an adjacent nozzle row are arranged in line, from assembly precision, a variation in distance between the ends of the adjacent nozzle rows becomes larger than a variation in distance between the nozzles, and it may cause a problem in printing quality.
Therefore, it is proposed that the ends of the adjacent nozzle rows be arranged to be overlapped. By doing so, in a region where nozzles are partly overlapped (hereinafter, referred to as an overlapping region), the amount of ink ejected per unit area can be controlled to be the same as the amount of ink ejected per unit area in a non-overlapping region. Also, it is possible to correct the discharge amount of ink in the nozzles in the overlapping region by arranging the ends of the adjacent nozzle row to be partially overlapped.
JP-A-2009-226904 discloses that the end of the first nozzle row and the end of the second nozzle row to be overlapped. JP-A-2010-188632 discloses a correction method of correcting the discharge amount of the ink.
The photocurable ink used in the photocurable ink jet printer has a property of being cured by light (ultraviolet light). Therefore, when the photocurable ink jet printer is in the standby state, the photocurable ink which remains in the nozzle is changed by environmental light. The changed photocurable ink may adhere to the nozzle and become foreign material.
When the foreign material adheres in the vicinity of the nozzle, as a result, the ink ejected is deflected and does not land in a desired position. If the ink does not land at the desired position, pixels occur in which ink lands multiple times or pixels occur in which no ink lands. In these regions, the concentration becomes lower, thereby decreasing the quality of the printing. In particular, in a region where the two overlapping nozzle rows form the image, in cases such as when ink is properly ejected from one nozzle row and deflection occurs in another array, this trend is noticeable.
In addition, in the region where plural overlapping nozzle rows form the image, since the deflection affects the meandering of the medium during transporting, the probability of forming the pixels in which the ink does not land further increases. Thus in the region where the nozzles of the plural overlapping nozzle rows form the image, it is desirable not to decrease the picture quality.